Common antenna for primary and secondary radar system

Abstract

A bifunctional antenna of a primary/secondary radar system comprises a reflector having a concave front surface formed with a row of slots along a horizontal generatrix, the slots lying in front of respective cavities excitable to radiate interrogation signals in a directive sum pattern and supplemental radiation in a differential control pattern designed to blank minor lobes of the interrogation pattern. Some of the cavities and slots are symmetrically duplicated on a dielectric cap covering the convex rear surface of the reflector. The reflector and its cap form a closed shell of dielectric material, specifically a glass mat impregnated with epoxy resin, overlain at the front by a fiber-glass fabric incorporating orthogonally intersecting insulated copper wires. The fabric also lines the inner walls of each cavity which is filled with dielectric material; its radiating slot is spanned only by horizontal wires paralleling the plane of polarization of target-seeking radiation from a source illuminating the reflector.

Dependencies are inferred from the claim text.